1. Field of the Invention
The present invention is directed to a method of selectively removing an aldehyde impurity from a process stream in the preparation of a substituted 8-arylquinoline. In particular, this invention is directed to a method of utilizing a polystyrene-based sulfonylhydrazine reactive resin to remove an aldehyde impurity in the preparation of a substituted 8-arylquinoline wherein the aryl group at the 8-position contains a substituent substituted-alkenyl group.
2. Related Background
Hormones are compounds that variously affect cellular activity. In many respects, hormones act as messengers to trigger specific cellular responses and activities. Many effects produced by hormones, however, are not caused by the singular effect of just the hormone. Instead, the hormone first binds to a receptor, thereby triggering the release of a second compound that goes on to affect the cellular activity. In this scenario, the hormone is known as the first messenger while the second compound is called the second messenger. Cyclic adenosine monophosphate (adenosine 3′,5′-cyclic monophosphate, “cAMP” or “cyclic AMP”) is known as a second messenger for hormones including epinephrine, glucagon, calcitonin, corticotrophin, lipotropin, luteinizing hormone, norepinephrine, parathyroid hormone, thyroid-stimulating hormone, and vasopressin. Thus, cAMP mediates cellular responses to hormones. Cyclic AMP also mediates cellular responses to various neurotransmitters.
Phosphodiesterases (“PDE”) are a family of enzymes that metabolize 3′,5′ cyclic nucleotides to 5′ nucleoside monophosphates, thereby terminating cAMP second messenger activity. A particular phosphodiesterase, phosphodiesterase-4 (“PDE4”, also known as “PDE-IV”), which is a high affinity, cAMP specific, type IV PDE, has generated interest as potential targets for the development of novel anti-asthmatic and anti-inflammatory compounds. PDE4 is known to exist as at lease four isoenzymes, each of which is encoded by a distinct gene. Each of the four known PDE4 gene products is believed to play varying roles in allergic and/or inflammatory responses. Thus, it is believed that inhibition of PDE4, particularly the specific PDE4 isoforms that produce detrimental responses, can beneficially affect allergy and inflammation symptoms. It would be desirable to provide novel compounds and compositions that inhibit PDE4 activity.
International Patent Publication WO9422852 describes quinolines as PDE4 inhibitors. U.S. Pat. No. 6,410,563 describes substituted 8-arylquinolines as PDE4 inhibitors.
However, there remains a need for methods to make such novel compounds without undesirable impurities.